Two glycoproteins of molecular weights of 62,000 and 36,000 have been purified to homogeneity from lavage material of patients with alveolar proteinosis as well as from lung lavage material and lamellar bodies from normal rabbits. These glycoproteins containing hydroxyproline, high content of glycine, sialic acid, mannose, galactose, fucose and N-acetylglucosamine, but no glucose or hydroxylysine. The carbohydrate sequence of these glycoproteins have been estabished. These glycoproteins were found to contain -Gly-Pro-Hyp-Gly- sequence in the peptide chain. The collagenous and non-collagenous peptides of these glycoproteins have been successfully separated and characterized. The data indicates that the non-collagenous peptides containing carbohydrates are located in the middle of the peptide chain whereas the N-terminal and C-terminal peptides represent the collagenous peptides of these glycoproteins. The present study confirmed that the glycoproteins of molecular weights of 36,000 was a proteolytic product of the glycoprotein of 62,000. It was also confirmed that these two glycoproteins were secretory products of alveolar Type II cells.